Atherectomy catheter with aligned imager

ABSTRACT

An atherectomy catheter is provided for excising and imaging material in a body lumen. In one embodiment, the catheter comprises a catheter body, a cutting blade, and an imaging device. The cutting blade is mounted on the catheter body and configured to move between a first position and a second position relative to an aperture or cutting window. When the cutting blade is in the second position, the blade substantially closes the aperture on the catheter body. The imaging device which is mounted on or otherwise coupled to the cutting blade is configured to be in an imaging position when the cutting blade substantially closes the aperture or cutter window. This allows the imaging device to survey material within the cutting zone of the atherectomy catheter. By allowing the imaging device to view materials within this cutting zone, material may be imaged and then removed from the body lumen without having to reposition the catheter between each step.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 09/930,372; filed onAug. 14, 2001 now U.S. Pat. No. 6,623,496, which is a continuation ofU.S. Ser. No. 09/378,224; filed on Aug. 19, 1999, now U.S. Pat. No.6,299,622, each of which is expressly incorporated herein in itsentirety by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to apparatus and methods forremoving occluding materials from body lumens. More particularly, thepresent invention relates to the construction and use of atherectomycatheters with an ability to view atheroma and other materials to beexcised from blood vessels.

Cardiovascular disease frequently arises from the accumulation ofatheromatous material on the inner walls of vascular lumens,particularly arterial lumens of the coronary and other vasculature,resulting in a condition known as atherosclerosis. Atherosclerosisoccurs naturally as a result of aging, but may also be aggravated byfactors such as diet, hypertension, heredity, vascular injury, and thelike. Atheromatous and other vascular deposits restrict blood flow andcan cause ischemia which, in acute cases, can result in myocardialinfarction. Atheromatous deposits can have widely varying properties,with some deposits being relatively soft and others being fibrous and/orcalcified. In the latter case, the deposits are frequently referred toas plaque.

Atherosclerosis can be treated in a variety of ways, including drugs,bypass surgery, and a variety of catheter-based approaches which rely onintravascular widening or removal of the atheromatous or other materialoccluding a blood vessel. Of particular interest to the presentinvention, a variety of methods for cutting or dislodging material andremoving such material from the blood vessel have been proposed,generally being referred to as atherectomy procedures. Atherectomycatheters intended to excise material from the blood vessel lumengenerally employ a rotatable and/or axially translatable cutting bladewhich can be advanced into or past the occlusive material in order tocut and separate such material from the blood vessel lumen. Inparticular, side-cutting atherectomy catheters generally employ ahousing having an aperture on one side, a blade which is rotated ortranslated by the aperture, and a balloon or other deflecting structureto urge the aperture against the material to be removed.

Although atherectomy catheters have proven to be very successful intreating many types of atherosclerosis, existing catheter designs may befurther improved to provide enhanced performance. For example, innibbler-type atherectomy catheters and in material excising devices ingeneral, it would be desirable to view the material to be removed priorto the removal step. Furthermore, it would be advantageous if thisimaging capability were provided on the same catheter or device whichperformed the cutting procedure, thus reducing the amount of surgerytime spent exchanging imaging and cutting devices. Although someexisting catheters provide imaging capability, these devices generallyrequire repositioning of the catheter and the cutting element betweenimaging and cutting procedures. This undesirably limits the ability ofthe surgeon to view the exact area of occlusive material to be removedprior to the cut. Such known devices also typically cause the user tofirst scan a large, less precise area of body lumen. It would bedesirable if the device could image the precise area to be excisedimmediately preceding the cut. Additionally, the repositioning of theentire catheter between imaging and cutting may cause the cuttingelement to remove material from a location different than the one thatwas imaged. This decreases the effectiveness of the cutters and mayaccidentally damage the body lumen. Known imaging atherectomy cathetersalso have difficulty imaging through the area of the cutting windowduring catheter delivery. The sharp edges of the cutter on knownatherectomy catheters are typically exposed during imaging and thusprevent simultaneous delivery and imaging by the device, since thoseexposed edges may accidentally catch and tear into the body lumen. Forexample, in U.S. Pat. No. 5,634,464, an imaging transducer is mounted ona rotatable cutter. Imaging can be performed either while the cutter isrotated or while it is merely axially translated (without rotation). Ineither case, the cutting blade is exposed during imaging.

For these reasons, it is desired to provide intravascular catheterswhich have imaging capability that enables a physician to differentiatebetween desirable tissue structure and undesirable fatty deposits to beremoved from a body lumen. It is desirable that the imaging and cuttingof material can occur without having to reposition the catheter betweensuch procedures. It would also be desirable if the atherectomy cathetercould interrogate and view the vessel while the cutter is deliveredthrough the body lumen or vasculature. It would still further bedesirable to provide atherectomy catheters having imaging capabilitieswhich can be utilized while the blade of the atherectomy device isunexposed to the blood vessel. At least some of these objectives will bemet by the catheter and method of the present invention describedhereinafter and in the claims.

SUMMARY OF THE INVENTION

The present invention provides catheters, kits, and methods for removingmaterial from a body lumen. More particularly, the present inventionprovides an atherectomy catheter, such as catheters having axiallytranslatable, non-rotating cutting blades, with an imaging capability sothat areas of the body lumen can be imaged and evaluated before thecutting procedure.

In a first aspect, the present invention provides a catheter for use inexcising material from a body lumen. The catheter comprises a catheterbody, a cutting blade, and an imaging device. The cutting blade ismounted on the catheter body and configured to move between a materialcapture (open) position and a closed position. When the cutting blade isin the closed position, the blade substantially closes an aperture or“cutting window” on the catheter body. The imaging device which isusually mounted on or coupled to the cutting blade is configured to bein an imaging position when the cutting blade substantially closes theaperture or cutter window. This allows the imaging device to surveymaterial within a “cutting zone” of the atherectomy catheter, preferablyprecisely at the location where severing of the material will occur,most preferably being aligned with the location of a cutting edge on thecutting blade when the blade is in the capture configuration. Byallowing the imaging device to view materials within this cutting zone,preferably precisely at the spot where severing of the material willoccur or be initiated, the material may be imaged and then removed fromthe body lumen without having to reposition the catheter between eachstep. Furthermore, by having the cutter blade in a substantially closedposition, the sharpened edges of the blade are not exposed to the tissueof the body lumen. This advantageously allows the catheter to imagetissue while the catheter is delivered through tortuous vasculaturewithout risk that the sharpened edge of the cutting blade willaccidentally penetrate tissue during the delivery process.

In one embodiment, the present invention provides a catheter having atelescoping cutting blade that extends outwardly from an aperture on thecatheter body. The cutting blade has a first open position leaving a gapbetween the blade and the catheter body to define a cutting window.Material targeted for removal will intrude into the cutter window and besheared off when the telescoping cutting blade is retracted into asecond closed position. The cutting window defined by the gap istypically a directional, side-opening cutting window. The materialimaging device is typically located at a distal end of the telescopingcutting blade. In this embodiment, the material imaging device canprovide information regarding the body lumen when the cutting blade isan open or a closed position.

In another embodiment, a catheter of the present invention comprises acatheter body having a side-opening aperture having a cutting blade forshearing off material that intrudes into the aperture or cutting window.A material imaging device is coupled to the cutting blade so that theimaging device will be in an imaging position when the bladesubstantially closes the cutting window. The imaging device in thisembodiment is located behind the cutting edge of the cutting blade.

In another aspect, the present invention provides a method for removingmaterial from a body lumen. The method comprises positioning a catheterbody having a cutting blade adjacent to a target material in the bodylumen. The cutting blade has a material imaging device and the blade ismounted on the catheter body to excise material which enters a cuttingwindow defined at least in part by the catheter body. The material isimaged when the cutting blade substantially closes the cutting window.It should be understood of course that the material imaging device couldbe a variety of sensors such as an ultrasound transducer array oroptical fibers for optical coherence tomography. The imaging typicallyoccurs prior to cutting. The cutting blade is then withdrawn to allowmaterial to intrude into the cutting window for cutting and removal.

In a still further aspect, kits according to the present invention willcomprise a catheter having a material imaging device. The kits willfurther include instructions for use setting forth a method as describedabove. Optionally, the kits will further include packaging suitable forcontaining the catheter and the instructions for use. Exemplarycontainers include pouches, trays, boxes, tubes, and the like. Theinstructions for use may be provided on a separate sheet of paper orother medium. Optionally, the instructions may be printed in whole or inpart on the packaging. Usually, at least the catheter will be providedin a sterilized condition. Other kit components, such as a guidewire ormaterial imaging accessories, may also be included.

A further understanding of the nature and advantages of the inventionwill become apparent by reference to the remaining portions of thespecification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an atherectomy catheter constructed inaccordance with the principles of the present invention.

FIGS. 2–5 show various embodiments of a catheter having a telescoping,material cutting element having a material imaging device according tothe present invention.

FIGS. 6A–6B are cross-sectional views of a material cutting devicehaving a material imaging device designed for use with a side-openingcutter window.

FIGS. 7A–8B depict embodiments of a material cutting device where thematerial imaging device extends outwardly from a forward-facing, distalopening on the catheter body.

FIGS. 9A–10B show embodiments of the catheter using a plurality ofimaging devices.

FIGS. 11A–12B show embodiments of the catheter having a material capturedevice and a material imaging device.

FIG. 13 shows a kit according to the present invention.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

The present invention is generally directed to excising material from abody lumen. More particularly, the present invention provides catheters,methods, and kits for imaging material to be removed from a body lumenprior to performing the removal or cutting procedure. The presentinvention advantageously allows for the imaging of material to be cutprior to the cutting or removal procedure. Furthermore, the material maybe imaged and then cut without requiring the repositioning of thecatheter body as commonly required in conventional intravascularcatheters.

Apparatus according to the present invention will comprise cathetershaving catheter bodies adapted for intraluminal introduction to thetarget body lumen. The dimensions and other physical characteristics ofthe catheter bodies will vary significantly depending on the body lumenwhich is to be accessed. In the exemplary case of atherectomy cathetersintended for intravascular introduction, the catheter bodies willtypically be very flexible and suitable for introduction over aguidewire to a target site within the vasculature. In particular,catheters can be intended for “over-the-wire” introduction when aguidewire lumen extends fully through the catheter body or for “rapidexchange” introduction where the guidewire lumen extends only through adistal portion of the catheter body.

Catheter bodies intended for intravascular introduction will typicallyhave a length in the range from 50 cm to 200 cm and an outer diameter inthe range from 1 French (0.33 mm; Fr.) to 12 Fr., usually from 3 Fr. to9 Fr. In the case of coronary catheters, the length is typically in therange from 125 to 200 cm, the diameter is preferably below 8 Fr., morepreferably below 7 Fr., and most preferably in the range from 2 Fr. to 7Fr. Catheter bodies will typically be composed of an organic polymerwhich is fabricated by conventional extrusion techniques. Suitablepolymers include polyvinylchloride, polyurethanes, polyesters,polytetrafluoroethylenes (PTFE), silicone rubbers, natural rubbers, andthe like. Optionally, the catheter body may be reinforced with braid,helical wires, axial filaments, or the like, in order to increaserotational strength, column strength, toughness, pushability, and thelike. Suitable catheter bodies may be formed by extrusion, with one ormore lumens being provided when desired. The catheter diameter can bemodified by heat expansion and shrinkage using conventional techniques.The resulting catheters will thus be suitable for introduction to thevascular system, often the coronary arteries, by conventionaltechniques.

The cutting blades used in the present invention will usually be formedfrom a metal, but could also be formed from hard plastics, ceramics, orcomposites of two or more materials, which can be honed or otherwiseformed into the desired cutting edge. In the exemplary embodiments, thecutting blades are formed as coaxial tubular blades with the cuttingedges defined in aligned apertures therein. It will be appreciated thatthe present invention is not limited to such preferred cutting bladeassemblies, in a variety of other designs, such as the use of wiperblades, scissor blades or the like. Optionally, the cutting edge ofeither or both the blades may be hardened, e.g., by application of acoating. A preferred coating material is titanium nitride, availablefrom Brycoat, Inc., which may be applied according to manufacturer'sinstructions.

The present invention may employ any of a wide variety of conventionalimaging devices and transducers. It will be particularly useful withphased array transducers of a type which may be deployed linearly orcircumferentially on the cutting blade. Linear deployment will allowviewing along a discrete length of the catheter axis, preferablyadjacent to the cutting point, usually over a length in the range from 1mm to 30 mm, preferably 2 mm to 10 mm. Circumferentially deployed phasedarrays may subtend a viewing arc in the range from 5° to 360°, usuallyfrom 180° to 360° in the case of telescoping cutters (e.g., FIGS. 1–5)or 90° to 180° in the case of window cutters (FIGS. 6A, 6B, 9A, 9B, 10A,10B, 11A, 11B, and 12A, 12B. The ability to image over a full 360° canbe achieved with the catheters having cutting blades which extend fullyfrom a fixed portion of the cutter assembly, such as those illustratedin FIGS. 2–4. For imaging transducers located on cutting blades within ahousing or second cutting element, the field of imaging will generallybe limited by the dimensions of the aperture. In some cases, however, itmight be possible to fabricate all or a portion of the cutterblade/housing out of an ultrasonically translucent material. In additionto ultrasonic array transducers, the imaging devices of the presentinvention may comprise optical coherence tomography devices, such asdescribed in U.S. Pat. No. 5,491,524, the full disclosure of which isincorporated herein by reference, as well as Huang et al. (1991) Science254:1178–1181; Brezinski et al. (1997) Heart 77:397–403; and Brezinskiet al (1996) Circulation 93:1206–1213. In some instances, the presentinvention may also provide optical imaging using optical wave guides andthe like.

Referring now to FIG. 1, a catheter 10 constructed in accordance withprinciples of the present invention, comprises a catheter body 12 havinga proximal end and a distal end 16. In the embodiment shown in FIG. 1, atelescoping cutting mechanism 18 is mounted on the distal end of thecatheter body. The cutting mechanism or cutting blade 18 has a proximalpointing cutting edge 20 which may be spaced apart from the catheterbody to define a cutting window 22. Preferably, the cutting mechanism 18has an atraumatic distal tip 24 to facilitate the introduction of thecatheter through a patient's vasculature. A proximal hub 30 is attachedto the proximal end of the catheter body and comprises aperfusion/aspiration connector 32, a guidewire connector 34, and aslider 36. The slider 36 is attached to the proximal end of an actuatorrod 37 which extends from the hub 30 through the lumen of catheter body12 into the cutting mechanism 18 where it is attached at a proximal endof the inner cutter 22. In this way, manual actuation of slider 36 inthe direction of arrow 38 moves inner cutter 22 in the direction ofarrow 40.

Referring now to FIGS. 2 and 3, the distal end 16 of the catheter shownin FIG. 1 will be described in further detail. FIG. 2 shows the cuttermechanism 18 in a first closed position relative to the catheter body12. In this position, the sharpened edges of the cutting mechanism 18 iscontained within the catheter body 12. The atraumatic distal tip 24 maybe equipped with a material imaging device such as an ultrasoundtransducer array or an optical coherence tomography device. In otherembodiments, a multiple, phased ultrasound array may be used to provideimaging. As can be seen in FIGS. 2 and 3, the material imaging device 50can provide images when the cutting blade or cutting mechanism 18 is ina first closed position as shown in FIG. 2 or in an open,material-engaging position as shown in FIG. 3. As best seen in FIG. 2,when the cutter mechanism 18 is closed, the imaging device 50 will lieadjacent to the leading edge of the catheter body 12, where the catheterbody acts as the second blade to effect severing of the material. Thus,the material imaging device 50 will be positioned right at the pointwhere material will be severed. The cutting edge 20 as shown in FIG. 3,typically includes a penetrating point 52 to facilitate materialcapture. By locating the material imaging device 50 on the cutting blade18, the present invention can move the imaging device through thevarious paths or cutting zones if the cutting blade were actuated. Thisability to move the imaging device 50 allows for imaging and cutting ofthe targeted material without having to reposition the catheter body 12which may cause misalignment of those materials imaged before cuttingand the actual location of the cutting zone. Of course, the materialimaging device 50 can be used at any point during the procedure, eitherbefore or after severing of the target material and an image could beproduced even while the cutting blade is being moved between the openand closed positions of the cutting mechanism 18.

The cutting edge 20 on the cutting blade 18 may be designed to have aplurality of penetrating points 52 as shown in FIG. 4 or may beotherwise configured to maximize material capture. Suitable cuttingblade and cutting edge designs can be found in commonly assignedcopending U.S. patent application Ser. No. 08/982,231 filed on Dec. 17,1997, which is incorporated herein by reference.

Referring now to FIG. 5, another embodiment of the cutting mechanism orcutting blade according to the present invention will now be described.As seen in FIG. 5, the cutting mechanism 70 may reciprocate as indicatedby arrows 72. This telescoping cutter mechanism 70 moves in a linearfashion to shear those materials which may enter the cutting window 74defined by the cutting edge 76 and the catheter body 12. A materialimaging device 50 is located in the tip of the cutting mechanism 70. Bylinearly reciprocating the cutting mechanism 70, a physician or operatorcould view the cut area pre-removal and post-removal without moving theentire catheter body. The cutting edge 76 of the present inventionincludes a plurality of penetrating points 80 which may angled or bentto pierce material in an effort to move the material in a certaindirection, such as toward the capture area as well as initiate thecutting of the material.

Although the embodiments described thus far show a telescope cuttingblade extending outwardly from a forward-facing aperture of a catheterbody, it should be understood that a variety of other configurations mayalso be adapted for use with a material imaging device. Referring now toFIGS. 6A and 6B, an atherectomy catheter 100 has an inner cutter 102mounted coaxially within an outer cutter 104 on the catheter body. Thecatheter 100 includes an atraumatic distal tip 106 to facilitateintroduction of the catheter through a patient's vasculature. As seen ifFIG. 6A, a material imaging device 110 is located on the inner cutter102. When the inner cutter or cutter blade is positioned to close thecutter window or aperture 112 (FIG. 6B) the imaging device 110 is inposition to survey materials in the cutting zone of the catheter 100. Inthis position, the physician can inspect the material to be removed andverify or fine tune the positioning of the catheter 100 to accuratelytarget material for removal. When it is verified that the catheter 100is in the proper position, the inner cutter 102 is moved to an openposition where a material may intrude into the cutting window oraperture 112 which will then be sheared off when the inner cutter isreciprocated to move into a closed position. A flex wire or flex circuit120 is connected to the material imaging device 110.

Referring now to FIGS. 7A and 7B, a material excising catheter having aside-opening cutting window 120 is equipped with a material imagingdevice 122 that extends outward from a forward-facing, distal apertureof a catheter body 124. The material imaging device 122 has a soft,atraumatic distal tip 126 to facilitate introduction through thepatient's vasculature. Positioning the imaging device 122 in the mannershown in FIG. 7A allows for full time 360° imaging for diagnosticpurposes. (Such a design allows for incorporation of an imaging devicewithout having to change the structure of the inner cutter 128 and mostof the catheter body 124.)

Referring now to FIGS. 8A and 8B, a still further embodiment of amaterial excising catheter will be described. As shown in FIG. 8A, thecatheter 140 has a material imaging device 142 mounted on the innercutter 144 and coupled to the atraumatic distal tip 146. The imagingdevice 142 is spaced apart from the distal tip, and thus differs fromthe embodiment shown in FIG. 1 through FIG. 3. The catheterconfiguration shown in FIGS. 8A and 8B, the imaging device is mounted tothe soft tip 146 and inner cutter 144 such that the target material oratheroma is viewed when the cutter is retracted (FIG. 8A). This allowsthe physician to view material through the cutter window prior to andafter the cutting procedure. Additionally, because the outer cutter 148has an open distal end 150 the material imaging device 142 can providefull time material imaging, whether the inner cutter is in a closed oran open position. The inner cutter 144, as shown in FIG. 8B, has a firstand second aperture 150 and 152. The side-opening aperture 150 isprovided for material removal while aperture 152 is provided for thematerial imaging device 142. In FIG. 8B, the material imaging device 142is fully extended outside the catheter body or outer cutter 148. In thisposition, the material imaging device 142 can be configured for partialor 360° material imaging.

Referring now to FIGS. 9A through 10B, still further embodiments of amaterial excising catheter according to the present invention will bedescribed. FIGS. 9A and 9B show a catheter 170 having a first materialimaging device 172 coupled to the soft, atraumatic distal end 174. Asecond material imaging device 178 is positioned opposite a side-openingcutter window 180 on the catheter body 176. The distal-most imagingdevice 172 can be used to image the vessel and make an initialdetermination of where to cut material from the vessel wall. Aftermaking the initial determination, the inner cutter 182 is moved to anopened position (FIG. 9B) the cutter window 180 will be opened and theimaging device 178 exposed so that-it may be used for imaging. Thecatheter will usually be repositioned so that the imaging device 178,which is located at the cutting position, is aligned with the materialoriginally located with the distal-most imaging device 172. Once it isverified that the target material to be removed is positioned within thecutting aperture, the inner cutter 182 may be translated to sever thematerial.

FIGS. 10A and 10B show a catheter 190 having a plurality of imagingdevices 192 and 194. Locations of these imaging devices are similar tothose described above for catheter 170 in FIGS. 9A and 9B, except thatthe second imaging device 194 is mounted on the inner cutter 196 insteadof on the catheter body 198. As seen in FIG. 10A, the second materialimaging device 194 is in an imaging position when the inner cutter 196has closed the side-opening cutter window 200 (FIG. 10A).Advantageously, by enclosing the cutting window 200 and drawing thesharpened edges of the cutter into the catheter body, the catheter 190may be delivered more smoothly through the vasculature with reduced riskthat one of those cutter edges will catch a body tissue, while thecatheter 190 can continue to image the vasculature during delivery.

FIGS. 11A through 12B show a preferred embodiment of the presentinvention having an imaging device 220 mounted on the inner cutter 222(FIG. 11B) for imaging material when the cutter window 224 is closed bythe inner cutter (FIG. 12B). As seen in FIGS. 11B and 12B, thisembodiment of the catheter includes a material capture device 226 and acam follower 228. A suitable material capture device for use with thepresent invention can be found in commonly assigned, copending U.S.patent application Ser. No. 09/377,844 filed on the same day as thepresent application, the full disclosure of which is incorporated hereinby reference. A flex wire 230 couples the material imaging device 220 tomonitoring devices located outside of the catheter. Imaging device 220may be an array of piezoelectric ultrasonic transducer elementsoperating in a frequency range between 20 MHz to 50 MHz. An exemplaryultrasonic transducer array is described in U.S. Pat. No. 4,917,097 toProudian et al., the full disclosure of which is incorporated herein byreference. The signals produced by the multiple elements may beprocessed in a conventional manner such as using a synthetic aperture toproduce an image of a sector of the vessel being treated. Usually, thesector will be about 90°, and the device can be rotated to provide alarger view (up to 360°) if desired.

It would also be possible to use rotating ultrasonic transducers, asdescribed in U.S. Pat. No. 5,902,245, the full disclosure of which isincorporated herein by reference, or a single element ultrasonictransducer, optionally to provide a moving B mode where the imagingpoint is moved over time. Moving B mode imaging may be particularlyuseful in treating in-stent restenosis where the struts or otherelements of the stent are readily apparent, even with such a simpleimaging approach. Other imaging approaches include angioscopy, e.g., asdescribed in U.S. Pat. No. 5,263,928, the full disclosure of which isincorporated herein by reference.

Referring now to FIG. 13, the present invention will further comprisekits including catheters 400, instructions for use 402, and packages404. Catheters 400 will generally be described above, and theinstruction for use (IFU) 402 will set forth any of the methodsdescribed above. Package 404 may be any conventional medical devicepackaging, including pouches, trays, boxes, tubes, or the like. Theinstructions for use 402 will usually be printed on a separate piece ofpaper, but may also be printed in whole or in part on a portion of thepackaging 404.

While all the above is a complete description of the preferredembodiments of the inventions, various alternatives, modifications, andequivalents may be used. Although the foregoing invention has beendescribed in detail for purposes of clarity of understanding, it will beobvious that certain modifications may be practiced within the scope ofthe appended claims.

1. A method of removing material from a body lumen, the methodcomprising: positioning a catheter comprising a tissue removal assemblycomprising a serrated cutting edge in a body lumen; rotating theserrated cutting edge of the tissue removal assembly; axially moving thetissue removal assembly in the catheter; directing the tissue removalassembly radially out of a cutting window in the catheter to removematerial from the body lumen.
 2. The method of claim 1 wherein thecatheter defines an outer diameter, wherein directing comprises movingthe tissue removal assembly radially out of the side-opening cuttingwindow beyond an outer diameter of the catheter.
 3. The method of claim1 wherein directing comprises moving at least part of the tissue removalassembly over a ramp disposed within the catheter.
 4. The method ofclaim 1 further comprising imaging the body lumen with an imaging devicedisposed on at least one of the catheter and tissue removal assembly. 5.A medical kit comprising: a catheter having a catheter body thatcomprises a cutting window, an outer diameter, and a movable tissueremoval assembly that can extend beyond the outer diameter of thecatheter body, wherein the tissue removal assembly comprises a serratedcutting blade comprising plurality of penetrating points; instructionsfor use in removing material from a body lumen comprising moving thetissue removal assembly between a first position in which the tissueremoval assembly is disposed within the catheter body and a secondposition in which at least a portion of the tissue removal assembly ispositioned beyond the outer diameter of the catheter body; and a packageadapted to contain the catheter and instructions for use.
 6. The kit ofclaim 5 wherein the tissue removal assembly comprises a cutting bladecomprising a non-serrated cutting edge.
 7. The kit of claim 5 whereinthe catheter further comprises an imaging device disposed on at leastone of the catheter body and tissue removal assembly.
 8. The kit ofclaim 5 wherein the instructions further comprise rotating the tissueremoval assembly.
 9. The kit of claim 5 wherein the catheter furthercomprises a cam disposed in the catheter body that directs the tissueremoval assembly from the first position to the second position.